System and method for reducing power consumption in an electronic device having a touch-sensitive display

ABSTRACT

A system and method for reducing power consumption in an electronic device by controlling the transition of the electronic device from a sleep mode to a full power mode. The electronic device comprises a main processor a touch-sensitive overlay, and an overlay controller. A sequence of touch inputs on the touch-sensitive overlay are detected and captured using the overlay controller while the main processor is in the sleep mode. A subset of the sequence of touch inputs is processed using the overlay controller to determine that the sequence of touch inputs corresponds to a coarse model of a pre-determined wake-up gesture prior to transitioning the electronic device from the sleep mode to the full power mode.

TECHNICAL FIELD

The present disclosure relates to electronic devices havingtouch-sensitive displays and the control of such electronic devices.

BACKGROUND

Electronic devices, including portable electronic devices, have gainedwidespread use and may provide a variety of functions including, forexample, telephonic, electronic messaging and other personal informationmanager PIM application functions. Portable electronic devices include,for example, several types of mobile stations such as simple cellulartelephones, smart telephones, wireless personal digital assistants PDAs,and laptop computers with wireless 802.11 or Bluetooth capabilities.

Portable electronic devices such as PDAs or smart telephones aregenerally intended for handheld use and ease of portability. Smallerdevices are generally desirable for portability. A touch-sensitivedisplay, also known as a touch screen or touchscreen display, isparticularly useful on handheld devices, which are small and havelimited space for user input and output. The information displayed onthe touch-sensitive displays may be modified depending on the functionsand operations being performed. With continued demand for decreased sizeof portable electronic devices, touch-sensitive displays continue todecrease in size.

Portable electronic devices can typically individually control powersupplied to different components of the device in order to save powerand increase battery. For example, in a full power mode, the maincomponents of the portable electronic device are supplied with power andare in an active state. In a sleep mode, one or more components of theportable electronic device are not supplied with power, or are suppliedwith reduced power, and are in an inactive state.

Portable electronic devices can be transitioned from full power mode tosleep mode, or from sleep mode to full power mode using a soft powercontrol system. For example, when the portable electronic device is infull power mode, a signal from an input key or a system softwaretime-out signal will transition the portable electronic device to sleepmode, or vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the attached figures, in which:

FIG. 1 is a simplified block diagram of one example of a portableelectronic device in accordance with the present disclosure;

FIG. 2 is a flow chart illustrating an example embodiment of a methodfor transitioning from sleep mode to full power mode based on a sequenceof touch inputs;

FIG. 3 is a flow chart illustrating additional processes for the methodshown in FIG. 2 according to an example embodiment of the presentdisclosure;

FIG. 4 is a flow chart illustrating additional processes for the methodshown in FIG. 2 according to another example embodiment of the presentdisclosure;

FIG. 5A is an illustration of a slow scan mode transitioning to a fastscan mode upon detection of a touch input;

FIG. 5B is an illustration of a duty cycle in a slow scan mode;

FIG. 5C is an illustration of a duty cycle in a fast scan mode;

FIG. 6 is an illustration of a wake-up gesture; and

FIG. 7 is an graphical representation of multiple repetitions of thewake-up gesture in FIG. 6.

DETAILED DESCRIPTION

An electronic device having a touch screen requires power in order towait for, record and then process every touch input to determine if therecorded touch input matches an input intended to wake-up the devicefrom an idle or sleep mode to a full-power mode. The power required forthe waiting and monitoring for a wake-up input or gesture can be a drainon the battery of the device. Improvements in electronic devices withtouch-sensitive displays are desirable. An improvement involvesproviding a method, and related system, that reduces power consumptionduring sleep mode while at the same time determining whether contactwith the touch-sensitive display was intended to transition theelectronic device to the full power mode.

The following disclosure describes a method and system for reducingpower consumption in an electronic device by controlling the transitionof the electronic device from a sleep mode to full power mode. Themethod and system determines whether a sequence of touch inputs on thetouch-sensitive overlay is intended to transition the electronic deviceto a full power mode from sleep mode.

Other aspects and features of the present disclosure will becomeapparent to those ordinarily skilled in the art upon review of thefollowing description of example embodiments in conjunction with theaccompanying figures.

For simplicity and clarity of illustration, reference numerals may berepeated among the figures to indicate corresponding or analogouselements. Numerous details are set forth to provide an understanding ofthe example embodiments described herein. The example embodiments may bepracticed without these details. In other instances, well-known methods,procedures, and components have not been described in detail to avoidobscuring the example embodiments described. The description is not tobe considered as limited to the scope of the example embodimentsdescribed herein.

The disclosure generally relates to an electronic device, which is aportable electronic device in the example embodiments described herein.Examples of portable electronic devices include mobile, or handheld,wireless communication devices such as pagers, cellular phones, cellularsmart-phones, wireless organizers, PDAs, wirelessly enabled notebookcomputers, netbooks, and so forth. The portable electronic device mayalso include devices, such as a handheld electronic game device, digitalphotograph album, digital camera, or other device.

A block diagram of an example of a portable electronic device 100 isshown in FIG. 1. The portable electronic device 100 includes multiplecomponents, such as a main processor 102 that controls the overalloperation of the portable electronic device 100. Communicationfunctions, including data and voice communications, are performedthrough a communication subsystem 104. Data received by the portableelectronic device 100 is decompressed and decrypted by a decoder 106.The communication subsystem 104 receives messages from, and sendsmessages to a wireless network 150. The wireless network 150 may be anytype of wireless network, including, but not limited to, data wirelessnetworks, voice wireless networks, and networks that support both voiceand data communications. A power source 142, such as one or morerechargeable batteries or a port to an external power supply, powers theportable electronic device 100.

The main processor 102 interacts with other components, such as RandomAccess Memory RAM 108, memory 110, a display 112 with a touch-sensitiveoverlay 114 operably connected to an overlay controller 116 thattogether comprise a touch-sensitive display 118, an auxiliaryinput/output I/O subsystem 124, a data port 126, a speaker 128, amicrophone 130, short-range communications 132, and other devicesubsystems 134. Interaction with a graphical user interface is performedthrough the touch-sensitive overlay 114. The main processor 102interacts with the touch-sensitive overlay 114 via the overlaycontroller 116. Information, such as text, characters, symbols, images,icons, and other items that may be displayed or rendered on a portableelectronic device, is displayed on the touch-sensitive display 118 viathe main processor 102. The main processor 102 may interact with anaccelerometer 136 that may be utilized to detect direction ofgravitational forces or gravity-induced reaction forces.

To identify a subscriber for network access, the portable electronicdevice 100 uses a Subscriber Identity Module or a Removable UserIdentity Module SIM/RUIM card 138 for communication with a network, suchas the wireless network 150. Alternatively, user identificationinformation may be programmed into memory 110.

The portable electronic device 100 includes an operating system 146 andsoftware programs or components 148 that are executed by the processor102 and are typically stored in a persistent, updatable store such asthe memory 110. Additional applications or programs may be loaded ontothe portable electronic device 100 through the wireless network 150, theauxiliary I/O subsystem 124, the data port 126, the short-rangecommunications subsystem 132, or any other suitable subsystem 134.

A received signal such as a text message, an e-mail message, or web pagedownload is processed by the communication subsystem 104 and input tothe processor 102. The main processor 102 processes the received signalfor output to the display 112 and/or to the auxiliary I/O subsystem 124.A subscriber may generate data items, for example e-mail messages, whichmay be transmitted over the wireless network 150 through thecommunication subsystem 104. For voice communications, the overalloperation of the portable electronic device 100 is similar. The speaker128 outputs audible information converted from electrical signals, andthe microphone 130 converts audible information into electrical signalsfor processing.

The touch-sensitive display 118 may be any suitable touch-sensitivedisplay, such as a capacitive, resistive, infrared, surface acousticwave SAW touch-sensitive display, strain gauge, optical imaging,dispersive signal technology, acoustic pulse recognition, and so forth,as known in the art. A capacitive touch-sensitive display includes acapacitive touch-sensitive overlay 114. The overlay 114 may be anassembly of multiple layers in a stack including, for example, asubstrate, a ground shield layer, a barrier layer, one or morecapacitive touch sensor layers separated by a substrate or otherbarrier, and a cover. The capacitive touch sensor layers may be anysuitable material, such as patterned indium tin oxide (ITO).

One or more touches, also known as touch contacts, touch inputs or touchevents, may be detected by the touch-sensitive display 118. The mainprocessor 102 and/or overlay controller 116 may determine and recordattributes of the touch, including a location of a touch, a time stampassociated with the touch, and a pressure associated with the touch etc.Touch location data may include an area of contact or a single point ofcontact, such as a point at or near a center of the area of contact. Thelocation of a detected touch may include x and y components, e.g.,horizontal and vertical components, respectively, with respect to one'sview of the touch-sensitive display 118. For example, the x locationcomponent may be determined by a signal generated from one touch sensor,and the y location component may be determined by a signal generatedfrom another touch sensor. A signal is provided to the overlaycontroller 116 in response to detection of a touch. A touch may bedetected from any suitable object, such as a finger, thumb, appendage,or other items, for example, a stylus, pen, or other pointer, dependingon the nature of the touch-sensitive display 118. Multiple simultaneoustouches may be detected.

One or more gestures may also be detected by the touch-sensitive display118. A gesture, such as a swipe, also known as a flick, is a particulartype of touch on a touch-sensitive display 118 that begins at an originpoint and continues to an end point. A gesture may be identified byattributes of the gesture, including the origin point, the end point,the distance traveled, the duration, the velocity, and the direction,for example. A gesture may be long or short in distance and/or duration.Two points of the gesture may be utilized to determine a direction ofthe gesture. A gesture may also include a hover. A hover may be a touchat a location that is generally unchanged over a period of time or isassociated with the same selection item for a period of time.

In sleep mode, one or more of the components of the portable electronicdevice 100 is not drawing power, or is drawing reduced power, from thebattery. The transition from sleep mode to full power mode may be madein a single step, or may be made over multiple steps. A wake-up gesturecan be utilized to transition the portable electronic device 100 fromsleep mode to full power mode. A wake-up gesture allows the user of theportable electronic device 100 to draw a gesture on the touch-sensitivedisplay 118 to wake up or unlock the portable electronic device 100 fromsleep mode. As described above, the wake-up gesture may be a sequence oftouch inputs within a predetermined duration of time. The wake-upgesture may include a sequence of substantially continuous touch eventsor a sequence of individual touch events within the predeterminedduration of time. The wake-up gesture may be any arbitrarily shapedgesture and may be set by the portable electronic device 100 duringinitial set up or by the user. For example, the wake-up gesture may beselected from a plurality of pre-recorded wake-up gestures stored in awake-up gesture library in the portable electronic device 100.Alternatively, the user can record a customized wake-up gesture that canbe added to the wake-up gesture library. The user-generated wake-upgesture or one of the pre-recoded wake-up gesture can then be selectedas the pre-determined wake-up gesture to transition the device from thesleep mode to the full-power mode.

A wake-up gesture can also be associated with a user profile such thatthe portable electronic device 100 presents a unique set of applicationscustomized according to the chosen user profile upon transitioning froma sleep mode to a full power mode. For example, for an individual user,one wake-up gesture may be associated with a work profile and anotherwake-up gesture may be associated with a personal profile. Each profilemay have a different home screen with a different set of applicationspresented therein.

In addition, the portable electronic device may be used by multipleusers, each having an associated wake-up gesture and a correspondingcustomized user profile.

Typically, processing every touch input to ascertain whether a touchinput is a part of a wake-up gesture is power intensive. In addition,the main processor must be operating in full power mode to process eachtouch input, even when the touch input may be unintentional, forexample, when the device is placed in a purse or a pocket. Routinely,the number of unintentional touch events exceeds the actual number ofwake-up or unlock gestures. Thus, a method and system for reducing powerconsumption in an electronic device by controlling the transition of theelectronic device from a sleep mode to a full power mode using a wake-upgesture is desirable.

According to one aspect of the present disclosure, the waiting for,recording and processing of a gesture to determine if the gesturecorresponds to a pre-determined wake-up gesture is accomplished bydistributing the processing of the touch inputs between the overlaycontroller 116 and the main processor 102. The overlay controller 116and the main processor 102 have different power consumption andprocessing capabilities.

The overlay controller 116, also referred to as the touch panelcontroller, may have resource-constraints, limited memory and a slowinterface compared to the host processor 102. Using the overlaycontroller 116 for preliminary gesture recognition, instead of the mainprocessor 102, results in lower power usage. As the overlay controller116 has limited processing capabilities, this advantageously results infurther reduction of power usage.

In an aspect, the method of reducing power consumption in the electronicdevice 100 is accomplished by controlling the transition of theelectronic device from a sleep mode to a full power mode as shown inFIG. 2. While the electronic device, including the main processor 102,is in the sleep mode (202), the touch-sensitive overlay 114 and theoverlay controller 116 can be maintained in full-power mode to detectand capture a sequence of touch inputs (or input gesture) on thetouch-sensitive overlay (204). The overlay controller 116 can process asubset of the sequence of touch inputs to determine whether the sequenceof touch inputs corresponds to a coarse model of a pre-determinedwake-up gesture (206). Upon determining that the subset of the sequenceof touch inputs matches a coarse model of the pre-determined wake-upgesture, the electronic device 100 can be transitioned from the sleepmode to the full power mode (212).

As described above, the overlay processor 116 has lower powerrequirements in comparison to the main processor 102. In order toadvantageously utilize the lower power requirements of the overlayprocessor, the present method uses the overlay controller or processor116 to monitor and capture touch inputs, including a sequence of touchinputs or gestures. Further, having regard to the limited processingcapabilities of the overlay processor, only a subset of the sequence oftouch inputs are used to compare to a coarse model of the pre-determinedwake-up gesture. For example, 50% of the touch inputs of the sequence oftouch inputs may be processed for determining whether the sequence oftouch inputs corresponds to a coarse model of a pre-determined wake-upgesture.

However, in some instances where a higher threshold of correspondencebetween the sequence of touch inputs and the pre-determined wake-upgesture is required, additional processing is desirable. For example,the wake-up gesture may also be used as a passcode for locking orunlocking the electronic device. In such instances, upon successfullymatching the input gesture with the pre-determined wake-up gesture usingcoarse models of the pre-determined wake-up gesture, the overlayprocessor may transition the main processor 102 to full power mode fromthe sleep mode (208), as shown in FIG. 3. The main processor 102 maythen process the entire sequence of touch inputs, or a substantial partthereof, to determine further correspondence with the pre-determinedwake-up gesture. This may be accomplished by comparing the entiresequence of the touch inputs to a fine model of the pre-determinedwake-up gesture. Upon successful determination of a match between theinput gesture and the fine model of the pre-determined wake-up gesture(210), the electronic device can be transitioned from the sleep mode tothe full power mode.

It is noted that the terms “coarse model” and “fine model” are usedherein to refer to the computational intensities required for featureextraction and classification. Typically, a coarse model check would bemore tolerant for determining feature correspondence than a fine model.That is, the coarse model check may act as a first-level check todetermine if a valid wake-up gesture is entered. On occasion, the coarsemodel check may result in a false-positive (resulting in a negativedetermination at the fine model check) or a false-negative (resulting inthe electronic device remaining in the locked-up state or sleep mode),but the coarse model check avoids initiating the more intensiveprocessing of a fine model check too frequently and the associatedbattery power consumption resulting in power savings.

It is recognized that running the touch-sensitive overlay 114 and theoverlay controller in the full power mode as described above inanticipation of touch inputs can be a drain on the battery power. Inorder to further reduce the power requirements associated with waitingfor, recording and processing the input gesture, during the sleep mode,the touch-sensitive overlay 114, the overlay controller 116, or both thetouch-sensitive overlay 114 and the overlay controller 116 can bemaintained in a slow scan mode (404), as shown in FIG. 4. The slow scanmode comprises duty cycling the touch-sensitive overlay 114 and/or theoverlay controller 116 between the full power mode for a first (oractive) period of time and the sleep mode for a second (or inactive)period of time. For reducing power consumption, the inactive period oftime is substantially longer than the active period of time. Touchevents are captured during the active period of time, when thetouch-sensitive overlay 114 and the overlay controller 116 are in thefull power mode.

Upon detecting a touch event (406), the touch-sensitive overlay 114 andoverlay controller 116 are transitioned to a fast scan mode (408). Thefast scan mode comprises duty cycling the touch-sensitive overlay 114and the overlay controller 116 between the full power mode for an activeperiod of time and the sleep mode for an inactive period of time, theinactive period of time in the fast scan mode being substantiallyshorter than the inactive period of time in the slow scan mode, tocapture the sequence of touch inputs.

Examples of duty cycling are illustrated in FIG. 5A through FIG. 5C.During a single duty cycle, the touch-sensitive overlay 114 and/or theoverlay controller 116 are powered at full power mode for an “active”period of time and then powered at the sleep mode or reduced power levelfor the remaining time i.e. an “inactive” period of time, as illustratedin FIG. 5A through FIG. 5C. In various example embodiments, the sleepmode power level may correspond to a power level below full powerdepending on the desired level of power savings, but sufficiently highto maintain memory in a retention mode, where memory content ispreserved but cannot be read out. Sleep mode is also known as a deepsleep mode.

The slow scan mode is a duty cycle where the active and inactive periodsare set to reduce power consumption, which may inherently reduce theaccuracy of capturing a gesture. The fast scan mode is a duty cyclewhere the active and inactive periods have been set to increase accuracyof capturing a gesture, which may thereby increase power consumption.FIG. 5A illustrates an embodiment where a gesture is recorded in a fastscan mode.

The active and inactive periods of time while duty cycling can be set inview of the typical lengths of various wake-up gestures. Detectionand/or capturing of short gestures can use a greater proportion ofactive periods vs. inactive periods, or can use shorter inactive periodsor both. Detection and/or capturing of long gestures can use a lowerproportion of active periods vs. inactive periods, or can use longerinactive periods, or both. The various time periods in the slow scanmode and the fast scan mode can be optimized based on thecharacteristics of the pre-determined wake up gesture, such as duration,complexity etc.

In various aspects of the present disclosure, once the overlaycontroller 116 detects a touch input, the touch-sensitive overlay 114and the overlay controller 116 are transitioned from a slow scan mode toa fast scan mode in order to capture the input gesture, as illustratedin FIG. 5A. In other aspects, when the overlay controller 116 detects atouch input, the touch-sensitive overlay 114 and overlay controller 116maintain their duty cycle and capture the gesture, for instance, whenthe touch-sensitive overlay 114 and the overlay controller 116 arealready in the fast scan mode, as shown in FIG. 5C.

Examples of slow and fast scan duty cycles are illustrated in FIG. 5Band FIG. 5C, respectively. FIG. 5B illustrates a slow scan duty cyclewith an inactive period that is substantially longer than the activeperiod. FIG. 5C illustrates a fast scan duty cycle with an inactiveperiod that is substantially shorter than the inactive period of theslow scan duty cycle illustrated in FIG. 5B. That is, in the fast scanduty cycle, the touch-sensitive overlay and the overlay controller areactive (at full power) more frequently.

In initial trials, the typical duration of gestures varied between 800ms to 2000 ms. During a slow scan mode, which is set to reduce powerconsumption, the initial part of the input gesture may be undetected.For instance, the input gesture of the first touch event of the sequenceof touch events may commence just as the touch-sensitive overlay 114 andthe overlay controller 116 transition from the full power mode to thesleep mode. The touch input will then be detected only during the activeperiod of the next duty cycle. Thus, the initial part of the inputgesture up to the time interval of inactive part of the duty cycle willnot be detected. However, the input gesture matching algorithms can bedesigned to tolerate such instances. For example, gesture matchingprocesses can tolerate up to 10-15% of missing or undetected inputs,i.e., the initial 80-120 ms of a short wake-up gesture of 800 msduration may go undetected and yet the input gestures can besuccessfully matched. Current limitations in electronics dictate that anactive period of 5 ms is needed for detecting a touch input. Thus, for agesture of 800 ms in duration, the slow scan duty cycle has to be 85-125ms (approximately 6% to 4% of active period per duty cycle). For longergestures, a slow scan mode with 2% active period per duty cycle maysuffice. Thus, the duration of a slow scan mode can be set based on thecharacteristics of the pre-determined wake-up gesture, such as itsduration or complexity.

It is observed that a typical touch event can be captured approximatelyevery 20 ms. Thus, a typical fast scan mode may have a 5 ms activeperiod and 15 ms inactive period (25% active period per duty cycle). Theduration of the active period is typically maintained at 5 ms, while theduration of the inactive period can be optimized based on the durationof the pre-determined wake-up gesture.

The overlay controller 116 can be used to capture the sequence of touchinputs or the input gesture as shown in FIG. 6. FIG. 7 shows multiplerepetitions of the input gesture illustrated in FIG. 6, which may beused, for example, to generate characteristics of a pre-determined wakeup gesture or for training purposes. The overlay controller 116 canstore the coordinates of points along the path of the input gesture, andthe related time stamps, in the overlay controller memory (not shown).When the overlay controller 116 is recording and/or initiallydetermining whether or not the recorded input gesture corresponds to thepre-determined wake-up gesture, only the touch-sensitive overlay 114 andthe overlay controller 116 draw power, while the remaining components ofthe portable electronic device 100 are in sleep mode. In FIG. 6, theblack dots correspond to captured touch events (also referred to astouch inputs or data points). In a coarse model (or a first ordermodel), the data points are connected by line segments and a match withthe pre-determined wake-up gesture may be determined based on anaccumulation of the length of the line segments. Whereas, in a finemodel, the curvatures of the input gesture and the pre-determinedwake-up gesture may be computed and more complex distance metrics may beused for the determination of a match.

As described earlier, the overlay controller 116 determines whether ornot the input gesture and the pre-determined wake-up gesture correspond,using a subset of the touch inputs, i.e., fewer data points than used bythe main processor 102. The main processor 102 can model the actual pathof the input gesture by interpolating the sequence of touch inputs witha fixed number of data points for a fine match.

Each touch input captured by the overlay controller 116 is associatedwith a measured parameter. The measured parameter may be a location ofthe touch input, a time stamp of the touch input or a pressure of thetouch input. The measured parameters of each of the touch inputs of thesequence of touch inputs forming the input gesture can be used fordetermining whether or not the input gesture corresponds to thepre-determined wake-up gesture. For coarse matching by the overlaycontroller 116, only a subset of the sequence of touch inputs is used,while the entire sequence of touch inputs, or a substantial partthereof, is used for fine matching by the main processor 102. Themeasured parameters of the touch inputs can be used to determine thetotal length, the total time duration, the sum of coordinate differencesbetween adjacent points in an x- and y-direction etc. of the inputgesture. In addition, velocity changes along the path, the standarddeviation in the x- or y-direction, or a combination of any of thesevariables, and comparing the determined variable(s) or parameter(s) withthe corresponding variable(s) for the pre-determined wake-up gesture.

For example, in a coarse match determination by the overlay controller116, the total time duration of the input gesture can be matched withthe total duration of the pre-determined wake-up gesture by using onlythe starting and ending touch inputs of the input gesture.

The input gesture can be said to correspond to the pre-determinedwake-up gesture when the difference between one or more measuredvariable(s) of the input gesture and the corresponding variable(s) ofthe pre-determined wake-up gesture is within a threshold differencelevel(s). For example, the input gesture can be determined to correspondto the pre-determined wake-up gesture when the difference between thelengths of the input gesture and the pre-recoded wake-up gesture is lessthan 5% of the length of the pre-determined wake-up gesture. In anotherexample, the input gesture can be determined to correspond to thepre-determined wake-up gesture when the difference between the totaltime durations of the input gesture and the pre-determined wake-upgesture is less than 10% of the total time duration of thepre-determined wake-up gesture. The threshold difference level of ameasured variable can be, independently from any other threshold errorlevel, 5%, 10%, 15% or 20% of the value of the corresponding variable ofthe pre-determined wake-up gesture.

If, after detecting a touch input, the overlay controller 116 does notdetect any further touch inputs on the touch-sensitive overlay within apredetermined period of time, the touch-sensitive overlay 114 and theoverlay controller 116 may be maintained in the slow scan mode for apredetermined lock-out period of time. This is advantageous when thereis a spurious or inadvertent touch input that does not correspond towake-up gesture. By maintaining the touch-sensitive overlay 114 and theoverlay controller 116 in the slow scan mode for a predeterminedlock-out period of time, unnecessary transitioning to the fast scan modeis prevented, thereby resulting in power savings.

Similarly, upon determining that the sequence of touch inputs does notcorrespond to the coarse model of the pre-determined wake-up gesture,the touch-sensitive overlay 114 and the overlay controller 116 may bemaintained in the slow scan mode for a predetermined lock-out period oftime. For example, touch inputs which do not correspond to thepre-determined wake-up gesture, can lead to undesirable powerconsumption. An unintended but continuous touch input could beconsidered an input gesture. In such a situation, the personalelectronic device 100 would transition to a fast scan mode and recordthe input gesture. Processing the unintended input gesture anddetermining that the unintended input gesture does not correspond to thepre-determined wake-up gesture would transition the personal electronicdevice back into the slow scan mode. However, since the touch input isunintended and continuous, the personal electronic device 100 wouldagain transition to the fast scan mode, undesirably consuming power. Inorder to avoid such repeated transition to fast scan mode, a time-out orlock-out period of time may be used. After the overlay controller 116determines that the input gesture does not correspond to thepre-determined wake-up gesture, the touch-sensitive overlay and theoverlay controller may be maintained in the slow scan mode for theduration of the lock-out period.

Any or all of (1) slow and fast scan modes having varying duty cycles,(2) rejection of non-gestures, (3) coarse match determination by theoverlay controller that the input gesture and the pre-determined wake-upgesture correspond, or (4) further processing by the main processor oncethe input gesture and the pre-determined wake-up gesture are coarsematched, can be used to reduce the power consumption of the portableelectronic device during a sleep mode while still determining whethercontact with the touch-sensitive display was intended to transition theportable electronic device to full power mode.

In the foregoing description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe present disclosure. However, it will be apparent to one skilled inthe art that these specific details are not required. In otherinstances, well-known electrical structures and circuits are shown inblock diagram form in order not to obscure the present disclosure. Forexample, specific details are not provided as to whether the embodimentsdescribed herein are implemented as a software routine, hardwarecircuit, firmware, or a combination thereof.

Example embodiments described herein may be represented as a softwareproduct stored in a machine-readable medium (also referred to as acomputer-readable medium, a processor-readable medium, or a computerusable medium having a computer readable program code embodied therein).The machine-readable medium may be any suitable tangible medium,including magnetic, optical, or electrical storage medium including adiskette, compact disk read only memory (CD-ROM), memory device(volatile or non-volatile), or similar storage mechanism. Themachine-readable medium may contain various sets of instructions, codesequences, configuration information, or other data, which, whenexecuted, cause a processor to perform steps in a method according to anembodiment. Those of ordinary skill in the art will appreciate thatother instructions and operations necessary to implement the describedembodiments may also be stored on the machine-readable medium. Softwarerunning from the machine readable medium may interface with circuitry toperform the described tasks.

While the example embodiments described herein are directed toparticular implementations of the portable electronic device and methodof controlling the portable electronic device, the above-describedembodiments are intended to be examples. Alterations, modifications andvariations may be effected to the particular embodiments by those ofskill in the art without departing from the scope of the presentdisclosure.

What is claimed is:
 1. A method for reducing power consumption in anelectronic device by controlling the transition of the electronic devicefrom a sleep mode to a full power mode, the electronic device comprisinga main processor, a touch-sensitive overlay, and an overlay controller,the method comprising: detecting and capturing a sequence of touchinputs on the touch-sensitive overlay using the overlay controller whilethe main processor is in the sleep mode; processing a subset of thesequence of touch inputs using the overlay controller to determine thatthe sequence of touch inputs corresponds to a coarse model of apre-determined wake-up gesture, the pre-determined wake-up gesture beingadapted to transition the electronic device from the sleep mode to thefull-power mode; transitioning the main processor from the sleep mode tothe full power mode; processing the entire sequence of touch inputsusing the main processor to determine that the sequence of touch inputscorresponds to a fine model of the pre-determined wake-up gesture totransition the electronic device from the sleep mode to the full powermode; and, transitioning the electronic device from the sleep mode tothe full power mode.
 2. The method of claim 1, wherein, prior tocapturing the sequence of touch inputs, the method further comprises:maintaining the touch-sensitive overlay and the overlay controller in aslow scan mode, the slow scan mode comprising duty cycling thetouch-sensitive overlay and the overlay controller between the fullpower mode for a first period of time and the sleep mode for a secondperiod of time, the second period of time being substantially longerthan the first period of time; and, upon detecting a touch input on thetouch-sensitive overlay, transitioning the touch-sensitive overlay andthe overlay controller to a fast scan mode, the fast scan modecomprising duty cycling the touch-sensitive overlay and the overlaycontroller between the full power mode for the first period of time andthe sleep mode for a third period of time, the third period of timebeing substantially shorter than the second period of time, to capturethe sequence of touch inputs.
 3. The method of claim 2, wherein upondetecting no further touch input on the touch-sensitive overlay within apredetermined period of time, maintaining the touch-sensitive overlayand the overlay controller in the slow scan mode for a predeterminedlock-out period of time.
 4. The method of claim 2, wherein, upondetermining that the sequence of touch inputs does not correspond to thecoarse model of the pre-determined wake-up gesture, maintaining thetouch-sensitive overlay and the overlay controller in the slow scan modefor a predetermined lock-out period of time.
 5. The method of claim 1,wherein each touch input of the sequence of touch inputs is associatedwith a measured parameter.
 6. The method of claim 5, wherein processingthe subset of the sequence of touch inputs using the overlay controllercomprises comparing the measured parameter of each touch input in thesubset of the sequence of touch inputs to a corresponding parameter ofthe coarse model of the pre-determined wake-up gesture.
 7. The method ofclaim 5, wherein processing the entire sequence of touch inputs usingthe main processor comprises comparing the measured parameter of eachtouch input in the entire sequence of touch inputs to a correspondingparameter of the fine model of the pre-determined wake-up gesture. 8.The method of claim 5, wherein the measured parameter is a location ofthe touch input, a time stamp of the touch input, or a pressure of thetouch input.
 9. The method of claim 1, wherein the pre-determinedwake-up gesture is selected from a plurality of pre-recorded wake-upgestures stored in a wake-up gesture library of the electronic device.10. The method of claim 1, wherein the pre-determined wake-up gesture isa user-generated wake-up gesture.
 11. The method of claim 1, wherein thepre-determined wake-up gesture corresponds to a user profile.
 12. Anelectronic device comprising: a main processor; a touch-sensitiveoverlay; and an overlay controller, the overlay controller beingconfigured to: detect and capture a sequence of touch inputs on thetouch-sensitive overlay while the main processor is in a sleep mode;process a subset of the sequence of touch inputs to determine that thesequence of touch inputs corresponds to a coarse model of apre-determined wake-up gesture, the pre-determined wake-up gesture beingadapted to transition the electronic device from the sleep mode to afull-power mode; transition the main processor from the sleep mode tothe full power mode, the main processor being configured to: process theentire sequence of touch inputs to determine that the wake-up gesturecorresponds to a fine model of the pre-determined wake-up gesture totransition the electronic device from the sleep mode to the full powermode; and, transition the electronic device from the sleep mode to thefull power mode.
 13. The electronic device of claim 12, wherein, priorto capturing the sequence of touch inputs, the touch-sensitive overlayand the overlay controller being configured to be maintained in a slowscan mode, the slow scan mode comprising duty cycling thetouch-sensitive overlay and the overlay controller between the fullpower mode for a first period of time and the sleep mode for a secondperiod of time, the second period of time being substantially longerthan the first period of time; and, upon detecting a touch input on thetouch-sensitive overlay, the touch-sensitive overlay and the overlaycontroller being configured to transition to a fast scan mode, the fastscan mode comprising duty cycling the touch-sensitive overlay and theoverlay controller between the full power mode for the first period oftime and the sleep mode for a third period of time, the third period oftime being substantially shorter than the second period of time, torecord the sequence of touch inputs.
 14. The electronic device of claim13, wherein upon detecting no further touch input on the touch-sensitiveoverlay within a predetermined period of time, the touch-sensitiveoverlay and the overlay controller being configured to be maintained inthe slow scan mode for a predetermined lock-out period of time; and upondetermining that the sequence of touch inputs does not correspond to thecoarse model of the pre-determined wake-up gesture, the touch-sensitiveoverlay and the overlay controller being configured to be maintained inthe slow scan mode for the predetermined lock-out period of time. 15.The electronic device of claim 12, wherein each touch input of thesequence of touch inputs is associated with a measured parameter. 16.The electronic device of claim 15, wherein processing the subset of thesequence of touch inputs comprises comparing the measured parameter ofeach touch input in the subset of the sequence of touch inputs to acorresponding parameter of the coarse model of the pre-determinedwake-up gesture; and processing the entire sequence of touch inputscomprises comparing the measured parameter of each touch input in theentire sequence of touch inputs to a corresponding parameter of the finemodel of the pre-determined wake-up gesture.
 17. The electronic deviceof claim 15, wherein the measured parameter is a location of the touchinput, a time stamp of the touch input, or a pressure of the touchinput.
 18. A computer-readable medium having tangibly recorded thereon aset of non-transitory instructions for execution by an electronic devicehaving a main processor, a touch-sensitive overlay, and an overlaycontroller, the non-transitory instructions for carrying out a methodfor reducing power consumption in the electronic device by controllingthe transition of the electronic device from a sleep mode to a fullpower mode, the method comprising: detecting and capturing a sequence oftouch inputs on the touch-sensitive overlay using the overlay controllerwhile the main processor is in the sleep mode; processing a subset ofthe sequence of touch inputs using the overlay controller to determinethat the sequence of touch inputs corresponds to a coarse model of apre-determined wake-up gesture, the pre-determined wake-up gesture beingadapted to transition the electronic device from the sleep mode to thefull-power mode; transitioning the main processor from the sleep mode tothe full power mode; processing the entire sequence of touch inputsusing the main processor to determine that the sequence of touch inputscorresponds to a fine model of the pre-determined wake-up gesture totransition the electronic device from the sleep mode to the full powermode; and, transitioning the electronic device from the sleep mode tothe full power mode.
 19. The computer-readable medium of claim 18,wherein, prior to capturing the sequence of touch inputs, the methodfurther comprises: maintaining the touch-sensitive overlay and theoverlay controller in a slow scan mode, the slow scan mode comprisingduty cycling the touch-sensitive overlay and the overlay controllerbetween the full power mode for a first period of time and the sleepmode for a second period of time, the second period of time beingsubstantially longer than the first period of time; and, upon detectinga touch input on the touch-sensitive overlay, transitioning thetouch-sensitive overlay and the overlay controller to a fast scan mode,the fast scan mode comprising duty cycling the touch-sensitive overlayand the overlay controller between the full power mode for the firstperiod of time and the sleep mode for a third period of time, the thirdperiod of time being substantially shorter than the second period oftime, to capture the sequence of touch inputs.
 20. The computer-readablemedium of claim 19, wherein upon detecting no further touch input on thetouch-sensitive overlay within a predetermined period of time,maintaining the touch-sensitive overlay and the overlay controller inthe slow scan mode for a predetermined lock-out period of time.